A vivarium is usually an enclosed area, which tries to resemble a natural habitat of a certain area.

An aquarium is a vivarium, simulating a water habitat, for instance a river, lake or sea, but only the submerged area of these natural habitats. A terrarium is a vivarium, simulating a dry habitat, for instance desert or savannah. A paludarium is a vivarium, simulating a rain forest or swamp environment. A riparium is a vivarium, simulating a river, this vivarium could also be seen as an aquarium interconnected with a terrarium, having both the underwater area as well as the shore, often used for aquatic lizards.

A vivarium may be small enough to sit on a desk or table, or may be a very large structure, possibly outdoors. Large vivaria, particularly those holding species capable of flight, typically include some sort of a dual-door mechanism for entry and exit, so that the outer door can be closed to prevent escape before the inner door is opened.